In many gas turbine engines, a secondary stream of air is extracted, or “bled”, from the main stream, typically in the cold section, for various uses. For example, in some engines, a secondary stream of cold, low-pressure air is extracted from the gas path of the compressor impeller, through a compressor shroud, and is used to pressurize and provide the air to the bearing cavities. When such engines are used in harsh environments, particles such as dust, sand or the like may be present in the main stream and the secondary bleed air stream, which is undesirable. Improvement is thus sought.